1. Field of the Invention
The present invention relates in general to a mounting arrangement for a wheel speed sensor and in particular to a wheel speed sensor having a frangible or bendable mounting spacer.
2. Description of Prior Developments
Wheel speed sensors are typically mounted to a wheel support, such as a steering knuckle, for providing a pulsed speed signal to an antilock brake system (ABS). The sensors are mounted to the wheel support with threaded fasteners such as bolts. The bolts are initially hand threaded into threaded bores formed in the wheel support and subsequently tightened using a tool such as an air driven socket wrench.
When the bolts are tightened, the wheel speed sensor is locked in alignment with a toothed pulse wheel or tone wheel that rotates with the vehicle wheel. Before leaving the vehicle assembly plant, the sensors are checked for proper alignment and proper mounting with respect to the steering knuckle and tone wheel. If the sensor is properly aligned with the tone wheel, electronic test fixtures will provide a signal indicative of proper alignment and a "closed" circuit. If the sensor is not properly aligned, an open circuit is indicated.
Unfortunately, a situation can arise where a sensor is mounted to the wheel support with a hand tightened bolt that is not fully seated by a tool such as an air wrench. In this case, the sensor can be properly aligned with the tone wheel, provide a positive test signal to a test apparatus, yet when placed in service, fall off the wheel support and generate a fault signal to the driver of the vehicle.
Accordingly, what is needed is a method and apparatus for mounting a speed sensor to a wheel support in such a manner that if the fastener which secures the sensor to the support is tightened by hand only, the sensor will be prevented from being properly aligned with the tone wheel. This in turn will prevent a test apparatus from providing an acceptable or positive indication that the sensor is properly installed. In this manner, the sensor cannot leave the vehicle assembly plant without being tightened by a tool, thereby preventing the subsequent loss or misalignment of the sensor due to insufficient torque applied to its mounting hardware.